Exam 15: Cell Signaling

Indicate true (T) and false (F) statements below regarding signaling in plants. Your answer would be a four-letter string composed of letters T and F only, e.g. TTTF. ( ) Since multicellularity evolved before the divergence of the plant and animal lineages, plants have homologs of most animal signaling proteins, such as nuclear receptors, Ras, JAK, and Notch. ( ) Receptor tyrosine kinases are the largest class of cell-surface receptors in plant cells. ( ) Both plants and animals use cyclic GMP, NO, and Ca²? for cell signaling. ( ) Leucine-rich repeat (LLR) receptor kinases are the most abundant type of receptor serine/threonine kinases in plants.

Indicate true (T) and false (F) statements below regarding the Ras-MAP-kinase signaling pathway. Your answer would be a four-letter string composed of letters T and F only, e.g. TTTF. ( ) The immediate early genes turn on a few hours after activation of the RTK. ( ) Ras-GTP binds directly to, and activates, the upstream kinase in the MAP kinase module. ( ) Signal transduction through the Ras-MAP-kinase pathway only leads to a transient response. ( ) In the MAP kinase module, Raf can be phosphorylated by Erk to create a negative feedback loop.

Indicate whether each of the following descriptions applies to visual signal transduction (V), olfactory signal transduction (O), or both (B). Your answer would be a four-letter string composed of letters V, O, and B only, e.g. VOVV. ( ) It involves cGMP as a second messenger . ( ) A rise in cyclic mononucleotide concentration follows the arrival of the signal. ( ) The signal is received by a G-protein-coupled receptor. ( ) An incoming signal leads to membrane hyperpolarization.